Wednesday, September 13, 2017

Endogamy, A Closer Look (Part 2)

This is the second post in a series examining 355 pairs of my own relatives who have tested, looking at how much DNA each shares in total as well as the size of the largest segment.  (First post in the series can be seen here and the third here.)

Everyone here has 100% Ashkenazic Jewish ancestry unless noted otherwise in the "Comments" column.  All numbers are as given by GedMatch with the exception of comparisons with Benjamin, JudithB, Shannon & Layla who are only on FamilyTreeDNA.

For each relationship section, I give the expected amount of shared centimorgans according to ISOGG.  I've also added in low/high ranges (at the 99th percentile) and average amounts shared according to the Shared Centimorgan Project (SCP) based on feedback to the first post.  In addition to looking at overall shared DNA for each pair, I also note the size of the longest shared segment.  Each relationship section gives the average amount of shared DNA and largest segment looking at those who have 100% Ashkenazic Jewish ancestry.
I have a LOT of potential matches.  What do real matches look like?

Second Cousins (212.5cM expected ISOGG; 46-515/233 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Beth / Sid33748 Beth 1/2 AJ
Beth / My father334.748 Beth 1/2 AJ
Susie / Beth363.539.2 Beth 1/2 AJ
JudithK / Ed198.128.1
JudithK / Scott358.745.7
JudithK / My mother252.245.7
Leslie / Ed171.640.8
Leslie / My mother249.248.3
Leon / Ed21332.1
Leon / Scott25534.4
Leon / My mother247.840.4
Sandy / Ed169.124.2Sandy 3/4 AJ
Sandy / My mother324.236Sandy 3/4 AJ
Sandy / Leslie244.157.7Sandy 3/4 AJ
Fern / Ed181.122.8
Fern / Scott245.952.1
Fern / My mother253.342
Fern / JudithK220.138
Fern / Leon247.648.2
Karen / Leslie273.940.4
Karen / Sandy174.936.1Sandy 3/4 AJ
Myron / Ken402.199.9
PatS / Ed183.742.1
PatS / My mother167.340.5
PatS / Karen185.925.2
Tara / Sid155.249.9
Tara / My father180.434.7
Tara / Beth178.539.8
Tara / Susie254.474.8
Jerry / Ed149.832.8
Jerry / Scott286.534.6
Jerry / My mother346.932.9
Jerry / Fern261.562.1
PaulaS / Beth218.246.8 Beth 1/2 AJ
PaulaS / Tara266.950.5
Berly / Beth183.346.7 Beth 1/2 AJ
Berly / Tara296.174.8
Myra / Leslie93.315.9
Myra / Myron281.437.6
Dan / Sid218.464.5
Dan / My father221.470.1
Dan / Beth69.721.3 Beth 1/2 AJ
Dan / Susie305.482.6
Dan / PaulaS266.671.8
Dan / Berly230.471.9
Hale / My grandmother374.763
DaveSr / Sid446.565.2DaveSr 1/2 AJ
DaveSr / My father658.193.9DaveSr 1/2 AJ
DaveSr / Susie589.566.3DaveSr 1/2 AJ
DaveSr / Tara136.319.7DaveSr 1/2 AJ
DaveSr / PaulaS202.129.2DaveSr 1/2 AJ
DaveSr / Berly238.842.7DaveSr 1/2 AJ
DaveSr / Dan72.516.6DaveSr 1/2 AJ
Debra / Dave185.838.6Dave & Debra 1/4 AJ
Debra / Liz180.629.7Liz & Debra 1/4 AJ
PattyBG / Dave30342PattyBG & Dave 1/4 AJ
PattyBG / Liz14931.2PattyBG & Liz 1/4 AJ
Benjamin / My grandmother26838
Marilyn / Ken291.288.1
Marilyn / Leslie195.345
Marilyn / Myra201.234.6
Average (for 100% AJ) 240.75cM 48.42cM

3/4 Second Cousins

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Don / Amy239.727.1
Average (for 100% AJ) 239.7cM 27.1cM

Half Second Cousins (106.25 expected ISOGG; 9-397/117)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Sue / Ken164.852.9
Myron / Sue151.626.9
Amy / Sid18778.3
Amy / My father21446.9
Amy / Susie160.546.9
PaulaS / Amy142.840.2
Berly / Amy7731.2
Myra / Sue108.227.8
Don / Sid139.546.3
Don / My father83.422.6
Don / Susie100.526.8
Don / PaulaS214.336.8
Don / Berly162.128.3
Marilyn / Sue232.964.2
Average (for 100% AJ) 152.76cM 41.15cM

Second Cousins Once Removed (106.25 expected ISOGG; 0-316/123 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Ken / Ed226.247.9
My mother / Ken275.158.6
Beth / Me21448 Beth 1/2 AJ
JudithK / Me195.345.2
Leslie / Me192.943.7
Leslie / Ken186.637.2
Leon / Me137.432.1
Ron / Ruth20968.5
Sandy / Me131.924.9 Sandy 3/4 AJ
Sandy / Ken128.428.5 Sandy 3/4 AJ
Fern / Me206.633.7
Karen / Ken165.258.3
Myron / Ed255.852.3
Myron / My mother147.919.8
Myron / Leslie121.819.2
Myron / Sandy125.949 Sandy 3/4 AJ
Myron / Karen14229.9
PatS / Me105.526.2
Sara / Ken236.847.1
Dave / Sid263.439.3 Dave 1/4 AJ
Dave / My father397.793.6 Dave 1/4 AJ
Dave / Susie409.539.8 Dave 1/4 AJ
Liz / Sid145.729 Liz 1/4 AJ
Liz / My father167.630.5 Liz 1/4 AJ
Liz / Susie265.230.5 Liz 1/4 AJ
Mark / Ed184.830.4 Mark 3/4 AJ
Mark / My mother189.330.4 Mark 3/4 AJ
Mark / Leslie140.735.3Mark 3/4 AJ
Mark / Karen10122.1Mark 3/4 AJ
Tara / Me134.734.2
Jerry / Me237.832.8
PaulaS / Dave63.129.1 Dave 1/4 AJ
PaulaS / Liz169.438 Liz 1/4 AJ
Berly / Dave73.643.1 Dave 1/4 AJ
Berly / Liz134.827.1 Liz 1/4 AJ
Myra / Ed157.920.2
Myra / My mother160.325.3
Myra / Sandy99.566.4 Sandy 3/4 AJ
Myra / Karen117.921.7
Myra / Sara275.555.8
Dan / Me147.734.7
Dan / Dave57.116.3 Dave 1/4 AJ
Dan / Liz71.131.3 Liz 1/4 AJ
Hale / Sid191.722.5
Hale / My father228.162.1
Hale / Susie226.553.9
DaveSr / Me433.465 DaveSr 1/2 AJ
Debra / Sid344.781.8 Debra 1/4 AJ
Debra / My father326.681.5 Debra 1/4 AJ
Debra / Susie323.481.5 Debra 1/4 AJ
Debra / Tara112.526.8 Debra 1/4 AJ
Debra / PaulaS199.446.8 Debra 1/4 AJ
Debra / Berly153.646.7 Debra 1/4 AJ
Debra / Dan120.123.6 Debra 1/4 AJ
PattyBG / Sid276.863.4PattyBG 1/4 AJ
PattyBG / My father284.163.1PattyBG 1/4 AJ
PattyBG / Susie29963.1PattyBG 1/4 AJ
PattyBG / Tara36.115.6PattyBG 1/4 AJ
PattyBG / PaulaS176.732.4PattyBG 1/4 AJ
PattyBG / Berly160.337.8PattyBG 1/4 AJ
PattyBG / Dan59.517PattyBG 1/4 AJ
Benjamin / Sid11629
Benjamin / My father16738
Benjamin / Susie19738
Elise / My grandmother236.146
Marilyn / Ed16152.3
Marilyn / My mother148.632.5
Marilyn / Sandy171.637.2 Sandy 3/4 AJ
Marilyn / Karen113.129.6
Average (for 100% AJ) 181.9cM 39.01cM

Half Second Cousins Once Removed (53.13 expected ISOGG; 0-341/73)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Sue / Ed12423.3
Sue / My mother106.423.3
Leslie / Sue16.99.3
Sandy / Sue89.119.8 Sandy 3/4 AJ
Karen / Sue59.712.1
Sara / Sue65.828.5
Amy / Me97.547.2
Don / Me69.722.5
Average (for 100% AJ) 77.14cM 23.74cM

Second Cousins Twice Removed (53.13 expected ISOGG; 0-261/74 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Ken / Me132.659.3
Myron / Me116.413.6
Mark / Ken180.746.6 Mark 3/4 AJ
Mark / Myron93.742.7 Mark 3/4 AJ
Myra / Me92.521.5
Myra / Mark106.233.9 Mark 3/4 AJ
Hale / Me147.635.9
Benjamin / Me17038
Marilyn / Me70.430.6
Marilyn / Mark16262.1Mark 3/4 AJ
Shannon / Sid9030Shannon 1/8 AJ
Shannon / My father11731Shannon 1/8 AJ
Shannon / Susie14331Shannon 1/8 AJ
Shannon / Tara00Shannon 1/8 AJ
Shannon / PaulaS7714Shannon 1/8 AJ
Shannon / Berly6921Shannon 1/8 AJ
Shannon / Dan4915Shannon 1/8 AJ
Average (for 100% AJ) 121.58cM 33.15cM

In general, as the relationships get more distant, it seems that the total shared DNA for the 100% Ashkenazi pairs is higher than expected either from ISOGG or the Shared Centimorgan Project.

Stay tuned for additional posts which will look at more distant relationships.  Lots more data to come!

Note:  I'm on Twitter.  Follow me (@larasgenealogy).

Want to get future blog posts emailed to you automatically?
Enter your email address:

Posted by at
Labels:

4 comments:

  1. AmySeptember 13, 2017 at 5:17 PM

    As I commented on your first post, it does seem that the greater the distance in the relationship, the bigger the disparity between the expected cM and those occurring among your kits. Not surprising given endogamy! Interesting!

    ReplyDelete
  2. MOCKBASeptember 13, 2017 at 5:54 PM

    Great, it is very encouraging. It means that up to the "actual" 3rd cousins, one shouldn't expect the extraordinary levels of spurious DNA sharing on the order of what you see in the broad population of false-positive DNA match hits

    ReplyDelete

Subscribe to: Post Comments (Atom)